International Publication No. 2002/039544 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 9-153734 (Patent Document 2) disclose antenna devices whose antenna characteristics are changed by changing a method of feeding using a single antenna (radiation element). An antenna device disclosed in Patent Document 1 includes means for changing the direction of a current flowing through a substrate by changing the position of feeding, by controlling whether or not grounding is performed, or by controlling whether feeding or grounding is performed, through switching of one or a plurality of switches. Patent Document 1 relates to a surface mount antenna.
FIG. 1 is a perspective view of a surface mount antenna disclosed in Patent Document 2. A surface mount antenna 10 includes a base body 1. An end surface 1a of the base body 1 includes a ground terminal 2 and a feeding terminal 3 formed thereon in such a manner as to be divided from each other, and an end surface 1b includes a capacitive loading electrode 4 formed thereon. On the surface of the base body 1, a strip line radiation electrode 5 whose two ends are respectively connected to the ground terminal 2 and the capacitive loading electrode 4 is formed and a feeding electrode 6 that connects a matching portion 5d of the radiation electrode 5 to the feeding terminal 3 is formed.